Metformin is one of the most widely used glucose-lowering drugs that is effectively used for the current treatment of type 2 diabetes mellitus. In addition to anti-diabetic action, metformin appears to possess important additional properties that may be pharmacologically relevant to long-term human health and welfare. Translational studies are therefore being undertaken in rodents within IRP, NIA, to evaluate potentially beneficial actions of metformin on a number of pharmacodynamics measures of relevance to health in rodents administered normal and assorted diets ? including high fat. Pharmacokinetics ? specifically, metformin blood and tissue levels are required to interpret pharmacodynamic data and aid in translation studies across species ? with an emphasis on humans. This Task Order supports the quantitative analysis of metformin drug levels in plasma and tissue samples generated in IRP NIA research studies.